Lens, light source unit, backlight apparatus, and display apparatus

ABSTRACT

A lens diffusing light emitted from a light source includes a concave light-incident surface, a light guide portion, and a light-emitting surface. The light-incident surface includes a plane portion opposed to the light source and an optical function portion that is formed on the plane portion and one of scatters and diffuses the light. The light emitted from the light source enters the light-incident surface. The light that has entered the light-incident surface passes through the light guide portion. The light-emitting surface emits the light passed through the light guide portion.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention claims the benefit under 35 U.S.C. §120 as adivisional application of U.S. patent application Ser. No. 12/366,066filed Feb. 5, 2009 under Attorney Docket No. 51459.70562US00 andentitled “Lens, Light Source Unit, Backlight Apparatus, and DisplayApparatus,” which contains subject matter related to Japanese PatentApplication JP 2008-034627 filed in the Japanese Patent Office on Feb.15, 2008. The entire contents of both of the above applications areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a backlight apparatus used in, forexample, a display apparatus, a lens used in the backlight apparatus, alight source unit, and a display apparatus equipped with the backlightapparatus.

2. Description of the Related Art

Currently, use of LEDs (Light Emitting Diodes) independent for each of R(red), G (green), and B (blue) has contributed to achieving an NTSC(National Television System Committee) ratio of 100% or more inbacklights of a high color range used for liquid crystal panels.Therefore, commodification of the backlights in PCs (PersonalComputers), amusement equipment, in-car equipment, and TVs is expected.

In a case of a middle- or large-sized backlight of 10 inches or more,for example, sufficient luminance and thinness are required to becompatible therein. Therefore, a new design of a direct LED backlightthat has been employed in the middle- or large-sized backlights isrequired. The direct LED backlight refers to a backlight of a type inwhich a plurality of LEDs as a light source are arrangedtwo-dimensionally and in parallel to a plane of the liquid crystalpanel.

In the case of the direct LED backlight, the number of LEDs to bemounted varies depending on which of a power-type LED and a normal-typeLED is used in relation to a light amount. When using the power-typeLEDs, it is difficult to dispose the LED elements independent for eachof R, G, and B close to each other due to the problem of the number,size, and heat of the LEDs. In other words, an increase in distancesamong the LED elements results in a disadvantage in mixing red light,green light, and blue light in a limited space. Also in this case,although not many problems are caused when a sufficient optical distance(thickness) can be secured, because it is currently difficult to bringthe LED elements close to each other due to the move towards reductionsin thickness, color variability is caused.

For reducing the thickness of the liquid crystal panel,side-emitting-type power LEDs of the related art are used in some cases.However, this case also has a limit in terms of color variability.

Meanwhile, when normal low-power LEDs are used, distances among RGBelements can be shortened. However, by merely using the LED elements asthey are even when the distances are shortened, generation of colorvariability right above the LEDs cannot be avoided in a backlightassuming thickness reduction. Moreover, a large variation in RGB lightdistribution characteristics of the respective LED elements facilitatescolor variability, which is a large problem.

For solving the problem on such color variability, there is disclosed,for example, a device including a plurality of point light sourcesarranged one-dimensionally and a cylindrical lens disposed above theplurality of point light sources and elongated in the one dimensionaldirection (see, for example, Japanese Patent Application Laid-open No.2006-286608 (paragraphs [0007] and [0009], FIG. 5); hereinafter,referred to as Patent Document 1). The cylindrical lens used in thisdevice includes a concave lens function (52) in a direction vertical toa substrate holding the point light sources (y direction). Further, thecylindrical lens includes a convex lens function (54) in a part of thehorizontal direction (x direction). With such a structure, light fromthe point light sources expands in a planar state even without a lightguide plate, whereby color variability is prevented.

SUMMARY OF THE INVENTION

In the cylindrical lens disclosed in Patent Document 1 above, light fromthe point light sources is diffused by the concave lens function (52).However, the cylindrical lens needs to be devised further for realizinga reduction in thickness of the display panel and suppressing luminancevariability or color variability.

In view of the circumstances as described above, there is a need for alens, a light source unit, a backlight apparatus, and a displayapparatus that are capable of efficiently mixing light from a lightsource and suppressing luminance variability or color variability.

According to an embodiment of the present invention, there is provided alens diffusing light emitted from a light source, including a concavelight-incident surface, a light guide portion, and a light-emittingsurface. The concave light-incident surface includes a plane portionopposed to the light source and an optical function portion that isformed on the plane portion and one of scatters and diffuses the light.The light emitted from the light source enters the light-incidentsurface. The light that has entered the light-incident surface passesthrough the light guide portion. The light-emitting surface emits thelight that has passed through the light guide portion.

When the lens according to the embodiment of the present invention isnot provided, for example, luminance of light that enters agenerally-used light guide plate or an optical sheet such as a diffusingsheet from the light source becomes partially high at a position rightabove the light source. In other words, luminance variability or colorvariability is caused. In the embodiment of the present invention, bythe optical function portion formed on the plane portion on thelight-incident surface, light that has entered the plane portion isscattered or diffused. Therefore, luminance variability or colorvariability can be suppressed. Moreover, provision of the opticalfunction portion on the plane portion makes processing and process ofthe lens for the scattering and diffusion easier at a time of productionof the lens.

The light source is provided either singly or plurally. As the lightsource, an element that emits light by an EL (Electro Luminescence)phenomenon, a cathode tube, or any other light-emitting element is used.The element that emits light by an EL phenomenon is an LED as adispersion-type EL element or an LED as a genuine EL element.

A single light source includes one or a plurality of light-emittingelements. When a single light source includes one light-emittingelement, the light emitted by that light-emitting element may be in anycolor. When a single light source includes a plurality of light-emittingelements, the light emitted from the light-emitting elements may bemonochromatic or may be in a plurality of colors (combination of colorsmay be changed as appropriate). When the light-emitting element is anLED, for example, a plurality of LEDs are realized in a single packagein some cases. In this case, a single light source may correspond to oneor a plurality of packages.

In the embodiment of the present invention, when a single light sourceemits monochromatic light, luminance variability is suppressed, and whena single light source emits light of two colors or more, luminancevariability and color variability are suppressed. Hereinafter, at leastone of the luminance variability and color variability will be simplyreferred to as light variability.

Reflectance (or absorptance) of light increases as a degree of “scatter”of light by the optical function portion increases, that is, as lightbeams advancing in the vertical direction toward the plane portionbecome less due to the scatter.

For example, the light source is constituted of a plurality oflight-emitting elements that are arranged in a predetermined directionand emit light by an EL phenomenon, and the lens is elongated in thepredetermined direction. In this case, the lens may have lightdistribution characteristics that are substantially the same in adirection orthogonal to the predetermined direction within a plane onwhich the plurality of light-emitting elements are arranged.

The optical function portion is a part that has been subjected to printprocessing or roughening processing. Accordingly, light is scattered ordiffused. Moreover, it becomes possible to adjust an amount of lightthat passes through the plane portion by the print processing.

The “roughening processing” includes processing of forming the planeportion into a prism-like surface, dot processing, blast processing, andthe like.

The “print processing” operates to scatter the light at a micro level.Thus, a part that has been subjected to the “print processing” may beincluded in a concept of the part that has been subjected to the“roughening processing”.

The light-emitting surface includes a part opposed to the plane portion,that has been subjected to the print processing. Because the printprocessing is performed on both the plane portion and a surface opposedto the plane portion, an effect of scattering the light is promoted andlight variability is suppressed. Alternatively, the light-emittingsurface includes a part opposed to the plane portion, that has beensubjected to the roughening processing.

The light-emitting surface is, for example, one of a cylindrical surfaceand a toroidal surface.

The lens may further include a bottom surface and one of a printprocessing portion and a roughening processing portion formed on thebottom surface. Alternatively, a reflective member, a reflective film,or the like only needs to be formed on the bottom surface of the lens.Accordingly, light beams can be increased at the light guide portion, tothus realize high luminance. The term “reflect” refers to not only thecase where light is reflected 100%, but also a case where part of thelight is transmitted through the bottom surface.

The light guide portion may contain a diffusing material. Accordingly,light from the light source can be efficiently diffused.

The lens further includes a heat flow path that is formed from thelight-incident surface to the light-emitting surface and discharges heatradiated from the light source. Accordingly, heat radiated from thelight source can be discharged to outside the lens.

The heat flow path may be provided from the plane portion to thelight-emitting surface, or from a part other than the plane portion tothe light-emitting surface.

The heat flow path may be a through-hole formed in the lens, or may beconstituted of a material having higher heat conductivity than aprinciple material of the lens.

According to another embodiment of the present invention, there isprovided a light source unit including a light source and a lens todiffuse light emitted from the light source. It is only necessary thatthe lens described above be used for the lens.

The light source unit further includes an optical member that is mountedon the light source and one of scatters and diffuses the light.Accordingly, light variability is suppressed. When using thelight-emitting element(s) that emits (emit) monochromatic light or lightin a plurality of colors as the light source, light distributioncharacteristics of a specific color can be enhanced. In other words, itbecomes possible to orient the light of a specific color from the lightsource in a desired direction, and cause the light to enter thelight-incident surface of the lens.

The optical member includes, for example, a sheet member. A prism sheet,a diffusing sheet, or the like is used as the sheet member.Alternatively, a sheet member whose surface has been subjected to thedot processing or the blast processing may be used.

The light source includes a light-emitting element to emit light by anEL phenomenon, and the optical member includes a sealing member to sealup the light-emitting element. Because the sealing member also functionsto scatter or diffuse the light from the light source, light variabilitycan be suppressed, the structure of which also contributes to thereduction in thickness of the light source.

The sealing member may contain a diffusing material.

The light source unit further includes a common substrate, thelight-emitting element of the light source is provided plurally, theplurality of light-emitting elements being arranged on the commonsubstrate, and the sealing member seals up each of the plurality oflight-emitting elements. In other words, the light source unit includesa so-called potting-type light source block.

A backlight apparatus according to an embodiment of the presentinvention includes a light source unit and a supporting member tosupport the light source unit.

A display apparatus according to an embodiment of the present inventionincludes the backlight apparatus and a light transmission control panelthat includes a plurality of pixels and controls transmission of thelight emitted from the backlight apparatus for each of the plurality ofpixels. A typical example of the light transmission control panel is aliquid crystal panel. However, the light transmission control panel maybe any panel as long as it can control the light transmission of thebacklight for each pixel.

As described above, according to the embodiments of the presentinvention, light from the light source can be efficiently mixed, andluminance variability or color variability can be suppressed.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a backlight apparatus according to anembodiment of the present invention;

FIG. 2 is a perspective diagram showing a part of a linear light source;

FIG. 3 is a plan view showing an LED block of this embodiment;

FIG. 4 is a cross-sectional diagram of a single light source unit thatis taken along the line A-A of FIG. 1;

FIG. 5 is a perspective diagram showing a lens seen from a bottomsurface thereof;

FIG. 6 is a simulation diagram showing a plurality of light beamspassing through the lens;

FIG. 7 is a simulation diagram showing the light beams passing throughthe lens, the lens being seen from a z-axis direction thereof;

FIG. 8 is a simulation diagram showing light beams from the LED block ina case where no lens of this embodiment is provided;

FIG. 9A is a simulation diagram showing light beams from the LED blocksto a diffusing plate in cases where the lens is provided;

FIG. 9B is a simulation diagram showing light beams from the LED blocksto a diffusing plate in cases where the lens is not provided;

FIG. 10 is a simulation diagram showing light beams in the case wherethe lens is provided in FIG. 9B, seen from above the diffusing plate;

FIG. 11A is a diagram showing TFs (Transfer Functions) on the diffusingplate in the case shown in FIG. 9A;

FIG. 11B is a diagram showing TFs (Transfer Functions) on the diffusingplate in the case shown in FIG. 9B;

FIG. 12 is a diagram showing a modification of the lens shown in FIGS. 4and 5;

FIG. 13 is a partially-enlarged diagram of a bottom surface of the lensshown in FIG. 12;

FIG. 14 is a cross-sectional diagram showing a lens according to anotherembodiment of the present invention;

FIG. 15 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention;

FIG. 16 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention;

FIG. 17 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention;

FIG. 18 is a cross-sectional diagram showing a light source unitaccording to still another embodiment of the present invention;

FIG. 19 is a cross-sectional diagram showing a light source unitaccording to still another embodiment of the present invention;

FIG. 20 is a photograph showing a state where light emitted from asingle light source unit shown in FIG. 19 is diffused by a diffusingplate;

FIG. 21 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention;

FIG. 22A is a diagram showing an LED block according to anotherembodiment that includes two green LEDs, a red LED, and a blue LED;

FIG. 22B is a diagram showing an LED block according to anotherembodiment that includes a red LED, a blue LED, and a green LED with alarger light-emitting area than the other LEDs;

FIG. 22C is a diagram showing an LED block according to anotherembodiment that includes a concave portion of a reflector for each offour LEDs;

FIG. 22D is a diagram showing an LED block according to anotherembodiment that includes a reflector having quadrangular concaveportions;

FIG. 23 is a cross-sectional diagram showing a light source unitaccording to still another embodiment of the present invention;

FIG. 24A is a perspective diagram showing the LED block;

FIG. 24B is a plan view of the LED block in FIG. 24A;

FIG. 25 is a plan view of a light source unit showing a state where aplurality of LED blocks are arranged inside a light-incident surface ofa lens;

FIG. 26 is a diagram showing RGB light distribution characteristics ofthe LED block;

FIG. 27A is a perspective diagram showing an LED block according tostill another embodiment of the present invention;

FIG. 27B is a plan view of the LED block in FIG. 27A;

FIG. 28 is a plan view of a light source unit showing a state where theLED block shown in FIG. 27 is arranged plurally inside a light-incidentsurface of a lens; and

FIG. 29 is a table showing a result of comparison between the LED blockshown in FIG. 24 and the LED block shown in FIG. 27.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

FIG. 1 is a diagram showing a backlight apparatus according to anembodiment of the present invention.

A backlight apparatus 10 includes a plurality of light source units 5and a supporting member 2 for supporting the light source units 5. Thebacklight apparatus 10 is applied to a display apparatus that uses alight transmission control panel (not shown). A typical example of thelight transmission control panel is a liquid crystal panel, though anypanel may be used as long as it can variably control light transmissionof a backlight for each pixel.

When the backlight apparatus 10 is applied to the display apparatus, anoptical sheet (not shown) such as a diffusing sheet and a prism sheet isinterposed between the backlight apparatus 10 and the light transmissioncontrol panel in some cases.

The supporting member 2 may be of a substrate type or a frame type, oralternatively be an assembly as a combination of two or more members.The supporting member 2 is formed of a resin, metal, or the like, but isnot limited thereto. A material having high heat conductivity such ascopper, aluminum, and carbon may be used as the material for thesupporting member 2, for diffusing heat radiated from the light sourceunits 5.

The plurality of light source units 5 are arranged in one direction,that is, laterally (x-axis direction) in FIG. 1, for example, to thusconstitute a single row of linear light source 15. By arranging aplurality of linear light sources 15 longitudinally (y-axis direction),the plurality of linear light sources 15 are arranged in a planar state.In the example of FIG. 1, a single row of linear light source 15includes 12 light source units 5, and a single backlight apparatus 10includes 6 rows of linear light sources 15. The number, arrangement,size, and the like of the light source units 5 and the linear lightsources 15 can be changed as appropriate.

As shown in FIG. 1, a single light source unit 5 includes a plurality of(6 in the example shown in FIG. 1) LED blocks 3 mounted on a base member4, and a lens 1 for diffusing light from the LED blocks 3. A single LEDblock 3 is constituted by packaging one or a plurality of LEDs 7. Asingle LED block 3 includes one or a plurality of LEDs 7 (see FIG. 3).However, a structure in which a single light source unit 5 includes asingle LED block 3 is also possible. A pitch of the LED blocks 3 isseveral mm to several ten mm, but is not limited thereto.

FIG. 2 is a perspective diagram showing a part of the linear lightsource 15. As shown in the figure, the linear light source 15 isconstituted by arranging the plurality of light source units 5. Althoughno gap is provided between the light source units 5 in the example ofFIG. 2, a predetermined gap may be provided between the light sourceunits 5. It should be noted that a power supply lead wire 6 is connectedto a back surface of each of the base members 4 of the linear lightsource 15.

When a single LED block 3 includes one LED 7, light emitted from thatLED 7 is monochromatic (white, red, green, blue, or any other color).The LEDs that respectively emit a plurality of colors are arrangedsequentially.

FIG. 3 is a plan view showing the LED block 3 of this embodiment. Asshown in the figure, each of the LED blocks 3 includes LEDs 7R, 7G, and7B for three colors of R, G, and B, and members including a substratefor supporting the LEDs 7R, 7G, and 7B, a reflector 8, and the like. TheLEDs 7R, 7G, and 7B are arranged in the x-axis direction.

The reflector 8 includes a concave portion 8 a, and the LEDs 7 aredisposed inside the concave portion 8 a. The reflector 8 is formed of amaterial having high reflectance for specular reflection (i.e., O-orderdiffraction), such as aluminum nitride. However, it is also possible forthe reflector 8 to be formed of aluminum, copper, iron, or stainlesssteel, or other materials. Alternatively, a material having high heatconductivity such as a carbon resin or metal other than those describedabove may be used for the reflector 8. Accordingly, accumulation of heatin the LED blocks 3 can be reduced and a large current can therefore beapplied to the LEDs 7.

FIG. 4 is a cross-sectional diagram of a single light source unit 5 thatis taken along the line A-A of FIG. 1. FIG. 5 is a perspective diagramshowing the lens 1 seen from a bottom surface thereof.

The lens 1 is elongated in a predetermined direction, that is, thex-axis direction, for example, in accordance with the number of LEDblocks 3 provided in the single light source unit 5. When the number ofLED blocks 3 is one, it is also possible that the lens 1 is elongated inthe y-axis direction. A length of the lens 1 in the x-axis direction isabout several ten mm, but can be changed as appropriate without beinglimited thereto. A length of the lens 1 in the y-axis direction is aboutseveral mm to several ten mm, but can be changed as appropriate withoutbeing limited thereto.

The lens 1 is elongated in the x-axis direction and has lightdistribution characteristics that are substantially the same in they-axis direction orthogonal to the x-axis direction within a plane onwhich the plurality of LEDs 7 are arranged.

For example, the lens 1 includes a concave light-incident surface 1 a, alight guide portion 1 b through which light that has entered thelight-incident surface 1 a passes, and a light-emitting surface 1 c foremitting the light. The light-incident surface 1 a, the light guideportion 1 b, and the light-emitting surface 1 c each have a shape thatis approximately constant in a longitudinal direction of the lens 1. Theplurality of LED blocks 3 are arranged along the longitudinal directionof the lens 1 such that the LEDs 7 emit light toward a concave portionformed by the light-incident surface 1 a. The light-emitting surface 1 cof the lens 1 includes, for example, a cylindrical surface (i.e.,partial sphere seen from an x-z plane in FIG. 4). The light-emittingsurface 1 c may instead be constituted of a toroidal surface, acombination of the cylindrical surface and a plane, a combination of thetoroidal surface and the plane, or other aspherical surfaces. In a caseof a lens including the toroidal surface, a lens having a radius, aconic coefficient, or an aspherical coefficient set for each chip sizeof the plurality of LEDs 7 may be used.

The light-incident surface 1 a includes a plane portion 1 d opposed tothe block of the LEDs 7. The plane portion 1 d is provided with a partincluding an optical function of scattering or diffusing light from theLED blocks 3. As shown in FIG. 5, for example, in this embodiment, theplane portion 1 d is provided with a print processing portion 12 thathas been subjected to print processing. During the print processing, theplane portion 1 d is printed in white or a color close to white, forexample, which makes it possible to adjust an amount of light thattransmits through the plane portion 1 d based on a printed state. Thecolor in the print processing is not limited to white or a color closeto white, and may be any color as long as it can at least scatter light.

It should be noted that the reflectance (or absorptance) of lightincreases as a degree of “scatter” of light in the plane portion 1 dincreases, that is, as light beams advancing in the vertical directiontoward the plane portion 1 d become less due to the scatter.

Glass, polycarbonate, olefin, or other resins is used as the materialfor the lens 1.

An operation of the light source unit 5 structured as described abovewill be described.

Light emitted from the each of the LED blocks 3 enters thelight-incident surface 1 a. Due to the concaveness of the light-incidentsurface 1 a, the light that has entered the light-incident surface 1 ais diffused and passed through the light guide portion 1 b as shown inFIG. 4. The light that has passed through the light guide portion 1 b isemitted from the light-emitting surface 1 c. Due to the convexedness ofthe light-emitting surface 1 c, the light emitted from thelight-emitting surface 1 c is diffused additionally.

FIG. 6 is a simulation diagram showing a plurality of light beamspassing through the lens 1. As can be seen from FIG. 6, due to a uniqueshape of the lens 1, the light emitted from the LED blocks 3 exits thelens 1 diffusely. FIG. 7 is a simulation diagram showing the light beamspassing through the lens 1, the lens 1 being seen from the z-axisdirection thereof. As can be seen from FIG. 7, in the light guideportion 1 b, light also advances in the longitudinal direction of thelens 1 or a direction close to the longitudinal direction. The lightreflected by the light-emitting surface 1 c out of the light that haspassed through the light guide portion 1 b advances toward a bottomsurface 1 e. When a reflective member or a reflective film is formed onthe bottom surface 1 e as will be described later, for example, thelight is reflected by the bottom surface 1 e.

Further, in the lens 1 of this embodiment, the light that advances inthe vertical direction (z-axis direction) or a near-vertical directionfrom the LED block 3 is scattered or diffused by the print processingportion 12 formed right above the LED block 3. Accordingly, the colorsof light are mixed effectively at a center portion of the light guideportion 1 b of the lens 1 (between the plane portion 1 d and a part ofthe light-emitting surface 1 c opposed thereto), thus resulting insuppression of luminance variability and color variability.

FIG. 8 is a simulation diagram showing light beams from the LED block 3in a case where the lens 1 of this embodiment is not provided. It can beseen from the comparison with the case of FIG. 8 that the lens 1 shownin FIG. 6 has less light beams that are emitted in the vertical ornear-vertical direction from the light-emitting surface 1 c of the lens1.

Moreover, although the lens 1 is of a small size, by providing a parthaving a plane surface, print processing to that plane portion 1 dbecomes easier.

In this embodiment, the LED blocks 3 are arranged linearly in the x-axisdirection and the lens 1 is elongated in the x-axis direction. Thus, thenumber of lenses 1 to be mounted on a single backlight apparatus 10 canbe reduced. Therefore, in production of the backlight apparatus 10, thenumber of processes for mounting the lenses 1 (processes for mountinglight source units 5) can be reduced, thus leading to a reduction incosts.

In this embodiment, because there is no need to use an expensive opticalmember such as a dichroic mirror, it becomes possible to realize aninexpensive backlight apparatus 10 and display apparatus.

For suppressing luminance variability, a diffusing sheet or a sheet forsuppressing luminance variability is generally used. In such a case, dueto deterioration of a light use efficiency, a large number of LEDs 7have been provided to thus maintain high luminance as a whole. In thisembodiment, however, because there is no need to use such a sheet forsuppressing luminance variability, desired luminance can be obtainedeven when the number of LEDs 7 is reduced.

FIGS. 9A and 9B are simulation diagrams respectively showing light beamsfrom the LED blocks 3 to a diffusing plate 13 in cases where the lens 1is and is not provided. The figures are diagrams seen from the x-axisdirection. FIG. 10 is a simulation diagram showing light beams in thecase where the lens 1 is provided in FIG. 9B, seen from above thediffusing plate 13. It can be seen that a larger amount of light beamsadvance in oblique directions out of the light beams emitted from thelens 1 in FIG. 9B than in FIG. 9A. In other words, the case where thelens 1 is provided has less luminance variability and color variabilityon the diffusing plate 13 than the case where the lens 1 is notprovided.

FIGS. 11A and 11B are diagrams showing TFs (Transfer Functions) of thelens shown in FIGS. 9A and 9B, respectively. In each of FIGS. 11A and11B, a graph represented by a solid line shows a TF of the lens in they-axis direction (see FIG. 4). A graph represented by a dashed lineshows a TF of the lens in the x-axis direction. When focusing on the TFin the y-axis direction represented by the solid line in particular, itcan be seen that, as shown in FIG. 11A, an FWHM (Full Width at HalfMaximum) in the case where the lens 1 is not provided is 50 mm or less.It can also be seen that, as shown in FIG. 11B, the FWHM is about 90 mmin the case where the lens 1 is provided.

As a modification of the lens 1, it is also possible to provide a printprocessing portion 12 b that has been subjected to the print processingon a bottom surface 21 e of a lens 21 as shown in FIG. 12. FIG. 13 is apartially-enlarged diagram of the bottom surface 21 e of the lens 21shown in FIG. 12. The lens 21 is different from the lens 1 in that theprint processing portion is provided on the bottom surface 21 e of thelens 21.

The print processing portion 12 b only needs to include, mainly, afunction of scattering or reflecting the light advancing toward thebottom surface 21 e out of the light that has passed through the lightguide portion 1 b. Therefore, light transmission of the print processingportion 12 b and that of a print processing portion 12 a at a planeportion 21 d may be different, or may be the same. It is also possibleto set the light transmission of the print processing portion 12 b onthe bottom surface 21 e to be smaller than that of the print processingportion 12 a at the plane portion 21 d.

Alternatively, a reflective member or a reflective film as a memberother than the member subjected to the print processing may be formed onthe bottom surfaces 1 e and 21 e of the lenses 1 and 21, respectively.For example, a reflective film formed of metal such as aluminum may beformed on the bottom surfaces 1 e and 21 e.

FIG. 14 is a cross-sectional diagram showing a lens according to anotherembodiment of the present invention. In descriptions below, descriptionson structures, functions, and the like similar to those of the lightsource unit 5 and the lens 1 of the embodiment shown in FIGS. 1 to 5etc. will be simplified or omitted, and points different therefrom willmainly be described.

As in the case of FIG. 4, FIG. 14 is a cross-sectional diagram seen fromthe x-axis direction. A lens 31 of this embodiment contains a diffusingmaterial 32. Due to the diffusing material 32 of the lens 31, light canbe efficiently diffused to thus suppress luminance variability and colorvariability. Particularly an effect of uniformizing and obscuring lightthat passes a center portion 31 f of the lens 31, that is, a partbetween a plane portion 31 d and a part of a light-emitting surface 31 copposed to the plane portion 31 d can be obtained.

The diffusing material 32 does not necessarily have to be contained inthe entire lens 31, but only needs to be contained in at least thecenter portion 31 f of the lens 31.

The following materials can be exemplified as the diffusing material 32.

Examples include cross-linked acrylic powder, acrylic ultrafine powder,cross-linked polystyrene particles, methyl silicone powder, cross-linkedstyrene particles, monodispersed cross-linked acrylic particles,cross-linked siloxane series, silver powder, titanium oxide, calciumcarbonate, barium sulfate, aluminum hydroxide, silica, glass, whitecarbon, talc, mica, magnesium oxide, and zinc oxide.

FIG. 15 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention. A roughening processingportion 44 that has been subjected to roughening processing is providedat a center portion (plane portion 41 d) on a light-incident surface 41a of a lens 41. Further, a roughening processing portion 46 similar tothe roughening processing portion 44 is provided on a light-emittingsurface 41 c of the lens 41. The roughening processing portions 44 and46 may be prism-like parts, or may be parts subjected to dot processingor blast processing. The roughening processing portions 44 and 46 mayalternatively be formed by processing different from each other (prism,dot, blast, etc.).

FIG. 16 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention. Roughening processingportions 54, 56, and 52 are respectively provided at a center portion(plane portion 51 d) of a light-incident surface 51 a of a lens 51, apart 51 g of a light-emitting surface 51 c opposed to the plane portion51 d, and a bottom surface 51 e. The roughening processing portions 54,56, and 52 are the same as that described in the embodiment shown inFIG. 15.

FIG. 17 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention. Print processing portions64 and 66 are respectively provided at a center portion (plane portion61 d) of a light-incident surface 61 a of a lens 61 and a part 61 g of alight-emitting surface 61 c opposed to the plane portion 61 d. The printprocessing portions 64 and 66 are the same as the print processingportion 12 of the embodiment shown in FIGS. 1 to 5.

FIG. 18 is a cross-sectional diagram showing a light source unitaccording to still another embodiment of the present invention. Anoptical member 26 for scattering or diffusing light from the LED blocks3 is mounted on the LED blocks 3 of a light source unit 25. A surface ofthe optical member 26 (surface from which light from the LEDs 7 isemitted) is subjected to, for example, the roughening processingdescribed above such as the prism processing, dot processing, and blastprocessing.

The optical member 26 may be used as, for example, a sealing member forsealing up the LEDs 7 (e.g., member for sealing the concave portion 8 aof the reflector 8). Accordingly, because the sealing member alsofunctions to scatter or diffuse the light from the LEDs 7, luminancevariability and color variability can be suppressed while contributingto a reduction in thickness of the light source unit 25. By using theoptical member 26 subjected to the prism processing, for example, it ispossible to prevent light of a certain color out of RGB and/or othercolors from advancing in the vertical or near-vertical direction. Thus,light distribution characteristics can be enhanced.

Examples of the material for the optical member 26 include a transparentsilicone resin, an olefin-based resin, other resins, and glass. It isalso possible for the optical member 26 to contain various diffusingmaterials described above.

In addition, a surface of the reflector 8 (e.g., surface of the concaveportion 8 a) of the LED blocks 3 may be subjected to the rougheningprocessing.

It is also possible to realize a lens constituted by combining at leasttwo feature parts of the lenses 1, 21, 31, 41, 51, and 61 and the lightsource unit 25 shown in FIGS. 1 (and FIGS. 2 to 5) and 12 to 18. FIG. 19is a cross-sectional diagram showing a light source unit according toone of the embodiments on the combinations, for example. In a lightsource unit 35, a plane portion 71 d and a bottom surface portion 71 eof a lens 71 are respectively provided with print processing portions 74and 72. Moreover, the lens 71 contains the diffusing material 32, andthe optical member 26 (e.g., prism sheet) is mounted on the LED block 3.

A part 71 g of a light-emitting surface 71 c of the lens 71 opposed tothe plane portion 71 d may be formed as a plane.

FIG. 20 is a photograph showing a state where light emitted from asingle light source unit 35 shown in FIG. 19, in which 6 LED blocks 3are provided, is diffused by a diffusing plate. In this example, an FWHMof 95 mm was obtained with respect to the TF on the diffusing plate. Theinventors of the present invention have conducted a similar experimenton a light source unit without the lens, which resulted in an FWHM of 42mm.

FIG. 21 is a cross-sectional diagram showing a lens according to stillanother embodiment of the present invention. At a center portion of alens 81, a heat flow path 81 h that is formed from a light-incidentsurface 81 a to a light-emitting surface 81 c and discharges heatradiated from the LED blocks 3 is provided. Accordingly, heat radiatedfrom the LED blocks 3 can be discharged to the outside of the lens.

Typically, the heat flow path 81 h is a through-hole penetrating thelens 81. However, it is also possible for the heat flow path 81 h to beformed of a material having higher heat conductivity than a principlematerial of the lens 81, such as metal and carbon. The number, size,shape, location, and the like of the heat flow path 81 h can be changedas appropriate.

It should be noted that the lens 81 shown in FIG. 21 is a lens providedwith a print processing portion 84 at a plane portion 81 d thereof.However, the heat flow path 81 h may also be provided in the lenses 21,31, 41, 51, 61, and 71 shown in the above embodiments.

FIGS. 22A to 22D are diagrams each showing an LED block according toanother embodiment of the present invention.

An LED block 23 shown in FIG. 22A includes an LED 7R, two LEDs 7G, andan LED 7B. Of the four LEDs 7, the two LEDs 7G disposed on both ends,for example, emit green light. A light source unit including the LEDblock 23 above typically includes a plurality of LED blocks 23 arrangedin a direction in which the LEDs 7 are arranged (x-axis direction), andis also elongated in the x-axis direction.

Of the three LEDs 7 in an LED block 33 shown in FIG. 22B, the LED 7G inthe middle is the largest. In other words, the LED 7G has a largerlight-emitting area than other LEDs 7. Though a concave portion 18 a ofa reflector 18 has an oval shape, the shape may of course be a circle.

In an LED block 43 shown in FIG. 22C, a concave portion 28 a of areflector 28 is provided to each of the four LEDs 7. Of the four LEDs 7,the LEDs 7G on both ends, for example, emit green light.

An LED block 53 shown in FIG. 22D includes a reflector 38 havingquadrangular (e.g., rectangular or quadrate) concave portions 38 a.

For the lenses of the light source units mounted with the LED blocks 23,33, 43, and 53 shown in FIGS. 22A to 22D, respectively, it is onlynecessary to employ the lens 1, 21, 31, 41, 51, 61, 71, or 81 of theabove embodiments, or a lens as a combination of at least two featureparts of those lenses.

FIG. 23 is a cross-sectional diagram showing a light source unitaccording to still another embodiment of the present invention.

An LED block 63 of a light source unit 45 is a potting-type LED block.FIG. 24A is a perspective diagram showing the LED block 63, and FIG. 24Bis a plan view thereof. The potting-type LED block 63 has a structure inwhich each of the plurality of LEDs 7 arranged in a row on a commonsubstrate 68 is sealed up.

A sealing member 36 is constituted of a transparent resin, glass, or thelike, and has a shape of, for example, a partial sphere, that is, thesealing member 36 has a function of a lens. The partial sphere istypically a hemisphere, but is not limited thereto. Further, instead ofa sphere, a toroidal surface or a multi-order curved surface of aquadratic surface or more may also be employed. The sealing member 36may be formed of the same material as the optical member 26, or may beformed of a different material. As the LEDs 7, typically, the LEDs 7Gare disposed on both ends and the two LEDs 7R and 7B are disposed in themiddle. The coloration, arrangement, number, and the like of the LEDs 7can be changed as appropriate.

FIG. 25 is a plan view showing a state where the plurality ofthus-structured LED blocks 63 are arranged inside a light-incidentsurface 100 a of a lens 100. As shown in FIG. 25, a single light sourceunit 45 typically includes the plurality of LED blocks 63 and one lens100. The number of LED blocks 63 to be contained in a single lightsource unit 45 can be changed as appropriate.

For the lens 100, it is only necessary to employ the lens 1, 21, 31, 41,51, 61, 71, or 81 of the above embodiments, or a lens as a combinationof at least two feature parts of those lenses.

Sizes a, b, and c shown in FIGS. 24B and 25 are 2 to 4 mm, 9 to 12 mm,and 9 to 15 mm, respectively, though not limited thereto.

By using such potting-type LED blocks 63, distributions of red (R)light, green (G) light, and blue (B) light become substantially the sameas shown in FIG. 23, for example, and mixing of colors with respect tothe diffusing plate is facilitated. Accordingly, color variability issuppressed. FIG. 26 is a diagram showing RGB light distributioncharacteristics of the LED block 63. As shown in FIG. 26, RGB lightdistribution close to Lambertian (uniform diffusion) is realized.

In particular, because the sealing member 36 of the LED block 63 isformed as a partial sphere, a multiple reflection caused by a totalreflection is suppressed, whereby a high light extraction efficiency canbe realized. Further, because the sealing member 36 is formed as thepartial sphere, a single LED becomes close to a linear light source at amacro level, whereby it becomes possible to fully exhibit the functionof a lens.

FIG. 27A is a perspective diagram showing an LED block according tostill another embodiment of the present invention, and FIG. 27B is aplan view thereof.

An LED block 73 includes a plurality of LEDs 7 arranged close to eachother, a case 99 for packaging the LEDs 7, and a sealing member 47 forsealing up the LEDs 7. In FIGS. 27A and 27B, the LEDs 7G, 7R, 7B, and 7Gare arranged in the stated order from the left-hand side. Thecoloration, arrangement, number, and the like of the LEDs 7 can bechanged as appropriate. The sealing member 47 is constituted of atransparent resin, glass, or the like, and an upper surface thereof is aplane without the function of a lens. However, it is also possible todesign the sealing member 47 in a shape that provides the function of alens.

As shown in FIG. 27B, a size d of the case 99 in the lateral directionis 6 to 9 mm, though not limited thereto.

FIG. 28 is a plan view of a light source unit showing a state where theplurality of LED blocks 73 are arranged inside the light-incidentsurface 100 a of the lens 100, as in the case of the light source unitshown in FIG. 25.

It should be noted that FIG. 29 is a table showing a result ofcomparison between the LED block 63 shown in FIG. 24 and the LED block73 shown in FIG. 27.

An embodiment of the present invention is not limited to the aboveembodiments, and various other embodiments may also be employed.

The above descriptions have been given on the case where the lightsource unit or the backlight apparatus 10 of the above embodiments isapplied to a display apparatus. However, the present invention is notlimited to the display apparatus, and the light source unit and thebacklight apparatus 10 can also be applied to billboards for commercialuse and billboards for advertisements.

As shown in FIGS. 1 and 2, in the above embodiments, each of the LEDblocks 3, 23, 33, 43, and 53 has been mounted on the base member 4, andthe base member 4 has been attached to the supporting member 2. However,it is also possible for the LED blocks 3, 23, 33, 43, and 53 (or LEDs 7)to be attached directly to the supporting member 2.

In FIGS. 22A to 22D, the examples in which the LED blocks 23, 33, 43,and 53 are each mounted with the LEDs 7 that respectively emit redlight, green light, and blue light have been described. However, the LEDblocks 23, 33, 43, and 53 that are each mounted with a white-color LEDare also applicable.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A lens configured to diffuse light emitted from alight source, the lens comprising: a concave light-incident surfaceincluding a plane portion opposed to the light source and an opticalfunction portion that is formed on the plane portion and scatters and/ordiffuses the light, and which at least a portion of the light emittedfrom the light source enters; a light guide portion through which thelight that has entered the light-incident surface passes; and alight-emitting surface configured to emit the light that passes throughthe light guide portion, wherein the light-emitting surface is acylindrical surface or a toroidal surface.
 2. The lens according toclaim 1, wherein the optical function portion is a part that has beensubjected to print processing.
 3. The lens according to claim 2, whereinthe light-emitting surface includes a part opposed to the plane portionthat has been subjected to the print processing.
 4. The lens accordingto claim 1, wherein the optical function portion is a part that has beensubjected to roughening processing.
 5. The lens according to claim 4,wherein the light-emitting surface includes a part opposed to the planeportion, that has been subjected to the roughening processing.
 6. Thelens according to claim 1, wherein the light-emitting surface includes apart opposed to the plane portion that has been subjected to rougheningprocessing.
 7. The lens according to claim 1, further comprising: abottom surface; and a print processing portion or a rougheningprocessing portion formed on the bottom surface.
 8. The lens accordingto claim 1, wherein the light guide portion comprises a diffusingmaterial for diffusing the light.
 9. The lens according to claim 1,further comprising a heat flow path that is formed from thelight-incident surface to the light-emitting surface and discharges heatradiated from the light source.
 10. The lens according to claim 1,wherein the light source comprises a plurality of light-emittingelements that are arranged in a predetermined direction and emit lightby an EL (Electro Luminescence) phenomenon, and wherein the lens iselongated in the predetermined direction.
 11. The lens according toclaim 10, wherein the lens has light distribution characteristics thatare substantially the same in a direction orthogonal to thepredetermined direction within a plane on which the plurality oflight-emitting elements are arranged.
 12. A light source unit,comprising: a light source; and a lens configured to diffuse lightemitted from the light source, the lens comprising: a concavelight-incident surface including a plane portion opposed to the lightsource and an optical function portion that is formed on the planeportion and scatters or diffuses the light, and which at least a portionof the light emitted from the light source enters, a light guide portionthrough which the light that has entered the light-incident surfacepasses, and a light-emitting surface configured to emit the light thatpasses through the light guide portion.
 13. The light source unitaccording to claim 12, further comprising: an optical member that ismounted on the light source and scatters and/or diffuses the light. 14.The light source unit according to claim 13, wherein the light sourcecomprises a light-emitting element to emit light by an EL phenomenon,and wherein the optical member includes a sealing member to seal up thelight-emitting element.
 15. The light source unit according to claim 14,wherein the optical member contains a diffusing material.
 16. The lightsource unit according to claim 14, further comprising: a commonsubstrate, wherein the light-emitting element of the light source isprovided plurally, the plurality of light-emitting elements beingarranged on the common substrate, and wherein the sealing member sealseach of the plurality of light-emitting elements.
 17. A backlightapparatus, comprising: a light source unit comprising a light source; =a lens to diffuse light emitted from the light source, the lenscomprising: a concave light-incident surface including a plane portionopposed to the light source and an optical function portion that isformed on the plane portion and scatters and/or diffuses the light, andwhich at least a portion of the light emitted from the light sourceenters, a light guide portion through which the light that has enteredthe light-incident surface passes, and a light-emitting surfaceconfigured to emit the light that passes through the light guideportion; and a supporting member to support the light source unit.
 18. Adisplay apparatus, comprising: a light source unit including a lightsource; a lens to diffuse light emitted from the light source, the lenscomprising: a concave light-incident surface including a plane portionopposed to the light source and an optical function portion that isformed on the plane portion and scatters and/or diffuses the light, andwhich the light emitted from the light source enters, a light guideportion through which the light that has entered the light-incidentsurface passes, and a light-emitting surface configured to emit thelight that passes through the light guide portion; a supporting memberto support the light source unit; and a light transmission control panelthat includes a plurality of pixels and controls transmission of thelight emitted from the lens for each of the plurality of pixels.